1) Field of the Invention
This invention relates to an insulating jacket having a vacuum zone and a getter composition within the zone. This jacket is useful to hold liquids in general and in particular aqueous and/or organic liquids such as coffee, tea, milk, broth, juices, wine, beer, other alcoholic beverage, refreshments, ice-cold soft drinks and other beverage needed to be kept for extended periods at a temperature higher or lower than room temperature. Other examples of liquids of this kind are aqueous or alcoholic solutions or suspensions, especially those of a pharmaceutical or biological nature. Additional examples are those of antifreeze products and radio isotopes. The jacket of the present invention can also be used for Dewar vessels and for cryogenic devices such as insulated piping, provided liquid hydrogen is not present.
2) The prior art
In Matsch et al U.K. Patent 921,273 ("Matsch") there is described a jacket with a composition of palladium oxide and a material selected from the group consisting of zeolite, charcoal and silica gel. The purpose of the Matsch composition is to maintain the desired vacuum level for a long time by sorption of the residual gases. The residual gases are mainly hydrogen, carbon monoxide and water.
Zeolites unfortunately have a limited sorption capacity for carbon dioxide. Zeolites have practically no sorption capacity for carbon monoxide and hydrogen. Zeolites exhibit poor water vapor sorption at super ambient temperatures. The activation of zeolites requires prolonged heat treatment which increases the expense of their use. Unfortunately the replacements of zeolites with charcoal and or silica gel does not result in any appreciable improvement.
In Boffito Italian Patent 1,191,114, there is suggested the use of certain alloys of zirconium resulting in a slight improvement. Unfortunately these prior art Boffito alloys do not have a sufficiently high sorptive capacity with respect to water vapor and the other residual gases. Furthermore the Boffito alloys require a high activation temperature of 573K or more. In such cases in order to minimize the gas load, the vessel has to undergo a prolonged heat treatment under pumping.